Backdrafting natural draft gas water heater

If you are concerned about Indoor Air Quality, get rid of your old school gas water heater. They often have backdrafting problems - meaning they suck air down the chimney. This can lead to carbon monoxide in the house.

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Comment by Nate Adams on October 29, 2015 at 11:46am

Judy, my point here was that the dryer running with the water heater alone firing is a very common occurrence. Worst case? 10 minutes/year, maybe?

I do dislike worst case draft testing a lot. If I'm testing a house on January 15th and it passes with flying colors, will it still pass August 15th? There's no way to know. Too much uncertainty. For a 45 minute test that I could spend doing something more likely to solve consumer problems, I'd rather look somewhere else.

Why even keep natural draft water heaters? I wrote an article recently "Why Gas Water Heaters Suck" that argues if you're going to do natural gas, do a sealed combustion unit. At that point, though, a heat pump water heater has a similar or lower first cost and similar operating costs, why even run the risk? Get rid of combustion.

Comment by Colin Genge on October 29, 2015 at 9:22am

You should not get much CO until the product of combustion (C02, water vapor, NOx) get reintroduced to the flame. Propane is used in warehouse fork lifts all day without a problem. The issue is not rapid death but slow death from the NOx which is essentially the dangerous chemical from smog that eats your lungs out in 20+ years. Smog also has lot of particulates that clog your lungs. Not good. That is how we get away with backdrafting continually without noticing it. 

If you were to backdraft into a closed furnace room, then you'd start to get more CO after a while.

Backdrafting wood burning fireplaces is much easier to do and has more powerful toxic gases and presents a larger if not as frequent a danger. 

Comment by Judy Rachel on October 17, 2015 at 8:37pm

Seriously, you are saying that configuring a home into worst case depressurization is not "legit".  That people will not be using their bath fans, kitchen fan and have the dryer running simultaneously.  It isn't relevant that the home "would not normally" be set up this way.  The point is the home could, unwittingly, be set up this way by the occupants and the consequences could be tragic.

Comment by tedkidd on October 15, 2015 at 8:09am
Expect this to happen when:

You tighten up your house,
You put in a ridge vent,
You burn wood in a fireplace,

Heat pump water heaters are much more efficient, safe, and getting really cheap.


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